Pump and combination pump and trap with snap-over mechanism and double-seal outlet valve

ABSTRACT

A combination pump and trap is disclosed which includes a snap-over mechanism useful for small floats with little buoyancy. The snap-over mechanism has a geometry in which the distance between the float or compression arm pivot point and the pivot for the portion of the spring connected to a first arm or toggle link is greater than the distance from the float or compression arm pivot point and the pivot for the portion of the spring connected to the float or compression arm. This geometry allows the magnification of buoyancy by the main arm which is transmitted to the first toggle link to be large and the magnification of buoyancy by the first toggle link which is transmitted to the change-over valve to be large. A trap which is connected to the float arm is also used, which allows a liquid seal to be maintained at the liquid discharge port. A double seal valve with a mechanism for allowing rapid opening of the valve upon movement of the float is also disclosed, as is a externally-cleanable working fluid feed valve.

This application is a division of U.S. patent application Ser. No.08/529,966 filed Sep. 19, 1995, now U.S. Pat. No. 5,655,888.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pump and trap for feeding a liquidsuch as water, fuel, etc. The pump and trap of the present invention issuitable particularly for use in collecting a condensate generated in asteam piping system and feeding this condensate to a boiler or a wasteheat recovery system.

2. Description of the Related Art

Condensate generated in a steam piping system in most cases still has aconsiderable quantity of heat. It therefore has been a widespreadpractice to provide a condensate recovery system, including a pump forrecovering the condensate and feeding it into a boiler or a waste heatrecovery system for the purpose of effective utilization of waste heatfrom the condensate, thus making effective use of this energy.

The pump used in prior art condensate recovery system collects thecondensate in a vessel, and then introduces a high-pressure workingfluid—such as steam—into the vessel by operating a change-over valve.The pressure of the high-pressure working fluid discharges thecondensate from the inside of the vessel. To insure high-efficiencyoperation of the pump, it is necessary to collect as much condensate aspossible within the vessel and to properly switch the change-over valve.

The pump of the prior art, therefore, generally adopts a snap mechanism,provided with a coil spring. in order to insure reliable switching ofthe change-over valve. A pump which is equipped with a built-in snapmechanism provided with a coil spring is disclosed in U.S. Pat. No.5,141,405, to Francart.

FIG. 13 is a front view of a snap mechanism used in the prior art pumpdescribed in the Francart patent. In the pump disclosed in the Francartpatent, the snap mechanism 100 comprises a main arm 101, a first arm102, and a coil compression spring 103. The main arm 101 is pivotallysupported, by a first shaft 106, on a supporting member or frame 105. Onthe forward end of the main arm 101 is connected a float 108, through ascrew member 104 which is fastened to the float 108.

The first arm 102 is connected at one end to the supporting member 105by the first shaft 106, and therefore to the main arm 101, and at theother end to one end of the coil spring 103 by a third shaft 110,through a spring bracket member 116. The other end of the coil spring103 is connected to the main arm 101 by a second shaft 112 through aspring bracket member 115. A valve spindle operating rod 111 isconnected by a shaft 107 to the center part of the first arm 102. Thevalve spindle (not shown) and the snapping mechanism 100 are linked tothe change-over valve through the valve spindle operating rod 111.

In the prior art pump, accumulation of condensate in the vessel (notshown) causes the float 108 to rise. As the float 108 rises, the springbracket member 115 side of the coil spring 103 moves upward, thuscompressing the coil spring 103. With further rise of the float 108, thecoil spring 103 is in line with the first arm 102. The float 108 risesfurther until an angle between the coil spring 103 and the first arm 102exceeds 180 degrees. As a result, the coil spring 103 suddenly recoversfrom compression, and the connecting section (the third shaft 110)between the coil spring 103 and the first arm 102 snaps downward. Thismovement results in downward movement of the valve spindle operating rod111 connected to the first arm to thereby suddenly switch thechange-over valve (not shown).

The prior art pump has a problem—notwithstanding its simple design andits ability to relatively efficiently pump liquid—that a great deal ofbuoyancy, or a large float, is needed to obtain a large force for properswitching of the change-over valve. This is because, in a triangleformed by the first shaft 106, the second shaft 112, and the third shaft110, the distance between the first shaft 106 and the second shaft 112is longer than that between the first shaft 106 and the third shaft 110.The distance between the first shaft 106 and the second shaft 112 islong, and accordingly the magnification of buoyancy produced by the mainarm 101 and transmitted to the first arm 102 is small. Furthermore,since the distance between the first shaft 106 and the third shaft 110is short, the magnification of buoyancy by the first arm 102 which istransmitted to the valve spindle operating rod 111 is also small.

SUMMARY OF THE INVENTION

In the view of the above-described disadvantages inherent to the priorart apparatus, it is an object of the present invention to provide apump which is capable of actuating the change-over valve with a largeforce, even with a float with little buoyancy, while still performingreliably.

The present invention features a pump in which a float, a change-overvalve, and a snap mechanism are built in a vessel having a working fluidinlet port, a working fluid discharge port, a liquid inlet port, and aliquid discharge port. The snap mechanism includes a first shaftpivotally supported within the vessel, a main arm rotating around thefirst shaft, a first toggle link rotating around the first shaft, asecond shaft pivotally supported functionally on the main arm at a pointspaced a small distance from the first shaft and parallel with the firstshaft, a third shaft pivotally supported functionally to the firsttoggle link at a point spaced a large distance from the first shaft andparallel with the first shaft, and a second toggle link mounted betweenthe second shaft and the third shaft and pivotable at both mountingpositions. A connecting mechanism functionally connects the float to themain arm at a point spaced from the first shaft, and another connectingmechanism functionally connects the change-over valve to the firsttoggle link. A compressible-expandable mechanism, which compresses tokeep the first toggle link at rest until the second shaft is alignedwith the first shaft and the third shaft, extends when the second shafthas gone beyond the position of alignment with the first shaft and thethird shaft, thus snapping to move the first toggle link.

In the pump of the present invention, accumulation of condensate in thevessel causes the float to rise to rotate the main arm around the firstshaft, and the second shaft moves between the first shaft and the thirdshaft until aligning with the first shaft and the third shaft, thuscompressing to deform the compressible-expandable mechanism. As thefloat goes further upward, the second shaft exceeds the position ofalignment with the first shaft and the third shaft and thecompressible-expandable mechanism suddenly extends to recover fromdeformation, thus snapping to move the third shaft. As a result, thechange-over valve is suddenly switched, allowing liquid accumulatedwithin the vessel to be pumped.

In the snap mechanism used in the pump of the present invention, thedistance between the first shaft and the third shaft is longer than thatbetween the first shaft and the second shaft. In a triangle formed bythe first shaft, the second shaft and the third shaft, the distancebetween the first shaft and the second shaft is short while the distancebetween the first shaft and third shaft is long; the magnification ofbuoyancy by the main arm which is transmitted to the first toggle linkis therefore large and the magnification of buoyancy by the first togglelink which is transmitted to the change-over valve is also large.Consequently, the change-over valve can operate properly with greatforce even when little buoyancy, i.e., a small float, is used.

The present invention also includes a valve at the liquid discharge portwhich acts as a trap for the vessel. The valve is connected to the floatmechanism, so that the valve opens when the float rises in response toaccumulation of liquid in the vessel. The valve ensures that a liquidseal is maintained at the liquid discharge port. The valve includes adouble seal, to equalize fluid pressure on the valve and therefore makeactuation of the valve easier. A mechanism for coupling the valve to thefloat is provided, as well as a mechanism for adjusting the double sealon the valve to ensure a good seal at both valve seats. The valvepreferably moves downward to unseat, to thereby allow less space to beused in the interior of the vessel by the valve.

The above and other subjects, features and advantages of the presentinvention will become more clear from the following description withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of a pumpaccording to the present invention;

FIG. 2 is an enlarged cross-sectional view of a snap mechanism sectionof FIG. 1;

FIG. 3 is an enlarged cross-sectional view of a float arm section withthe float in a raised position;

FIG. 4 is a cross-sectional view taken along line A—A of FIG. 2;

FIG. 5 is a cross-sectional view of a second embodiment according to thepresent invention;

FIG. 6 is a cross-sectional view of a third embodiment according to thepresent invention;

FIG. 7 is a cross-sectional view of a fourth embodiment according to thepresent invention;

FIG. 8 is a cross-sectional view of another snap mechanism sectionaccording to the present invention;

FIG. 9 is a cross-sectional view taken along line B—B of FIG. 8;

FIG. 10 is a cross-sectional view of another snap mechanism sectionaccording to the present invention;

FIG. 11 is an exploded perspective view of a main arm and a connectingmember in FIG. 10;

FIG. 12 is a cross-sectional view of another snap mechanism according tothe present invention; and

FIG. 13 is a cross-sectional view of a snap mechanism section in a priorart pump;

FIGS. 14A-14C show a cross-sectional side view and end views of thelower valve head of the present invention;

FIG. 15 shows a cross-sectional side view of the connecting tube of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a cross-sectional view of a first embodiment of thecombination pump and trap of the present invention. FIG. 2 is anenlarged sectional view of the snap mechanism of FIG. 1. FIG. 3 is anenlarged sectional view of the snap mechanism with the float of FIG. 1in a raised position. FIG. 4 is a sectional view taken along line A—A ofFIG. 2. In FIG. 1, the pump 1 of the embodiment of FIG. 1 includes afloat 3, a change-over valve 4, a snap mechanism 5, and a valve 6, allof which are disposed within a vessel 2.

In the vessel 2 a body section 7 and a cover section 8 are connected byscrews (not shown), and a liquid holding space 10 is formed inside. Inthe embodiment of FIG. 1, the body section 7 of the vessel 2 has nocomponents mounted thereon; distinctive components of the embodiment aremounted on the cover section 8 of the vessel 2. The cover section 8 isprovided with four openings: a working fluid inlet port 11, a workingfluid outlet port 13, a liquid inlet port 16, and a liquid dischargeport 17.

Inside the working fluid inlet port 11, a working fluid feed valve 20 ismounted, and inside of the working fluid outlet port 13, a working fluidexhaust valve 21 is mounted. The working fluid feed valve 20 is composedof a valve case 22, a valve head 23, and a valve lifting rod 24. Thevalve case 22 has a through hole provided in an axial direction; theupper end of the through hole functions as a valve seat 25. In theintermediate part of the valve case 22 four openings 26, connecting thethrough hole with the liquid holding space 10, are provided. The valvehead 23 is of a semi-spherical or spherical form and is integrallyinstalled at the tip of the valve lifting rod 24.

The working fluid feed valve 20 is particularly adapted to easy cleaningwithout disassembly of the vessel 2. A sealing cap C is removablymounted, preferably by screw threads, on cover section 8 above valvehead 23, thereby allowing access to the working fluid feed valve 20interior. A screen S may surround the valve head 23 to trap particles toprevent the particles from clogging the working fluid feed valve 20. Thevalve head 23 and valve lifting rod 24, integrally formed together, canbe removed as a unit through the hole through cover section 8 into whichthe sealing cap is mounted. This ability is in part due to the absenceof a fixed connection between valve lifting rod 24 and connecting plate27. This lack of a fixed connection also allows the working fluid feedvalve 20 to be manufactured without the need for tight tolerancingbetween the valve lifting rod 24 and the valve spindle operating rod 28.The valve case 22 can thereafter be removed from the cover section 8through the same hole. Accordingly, each of the elements of workingfluid feed valve 20 may be removed and cleaned externally of the vessel2, without the need to separate cover section 8 and body section 7.

In the pump 1 of the present invention, the tip of the valve case 22 ofthe working fluid feed valve 20 is screwed into the working fluid inletport 11. The valve head 23 is located on the working fluid inlet port 11side, and the valve lifting rod 24 is inserted through the through holein the valve case 22 to the vessel 2 side into contact with a connectingplate 27. The connecting plate 27 is connected to valve spindleoperating rod 28. The valve spindle operating rod 28 is connected to thesnap mechanism 5.

The working fluid exhaust valve 21 is composed of a valve case 29, avalve head 30, and a valve lifting rod 31. The valve case 29 has athrough hole in an axial direction, in which a valve seat 32 isprovided. The valve head 30 secured on the tip of the valve lifting rod31 comes from below into contact with the valve seat 32, thus openingand closing the valve. The valve spindle operating rod 28 and the valvelifting rod 31 are connected by a pin 33. The change-over valve 4includes the working fluid feed valve 20 and the working fluid exhaustvalve 21; when the working fluid feed valve 20 is opened, the workingfluid valve 21 is closed, and when the working fluid feed valve 20 isclosed, the working fluid exhaust valve 21 is opened. Any pressurizedfluid may be used as the working fluid to power pump 1.

The liquid inlet port 16 is located nearly at the center of the coversection 8 and the liquid discharge port 17 is in a positioncorresponding to the lower part of the vessel 2. The float 3 issupported by a bracket 36 through a float arm 34 and a shaft 35. Thesnap mechanism 5 is supported on a bracket 38 through a first shaft 37.The bracket 36 and the bracket 38 are connected by screws (not shown),and are integrally attached to the cover section 8 of the vessel 2. Thefloat arm 34 is produced from a plate bent into a U shape, so that twoparallel plates will face each other as shown in FIG. 4. The float 3 isconnected to the bent section of the float arm 34; to the other end ofthe float arm 34 is connected a shaft 40.

The bracket 36 as viewed from above is composed of two L-shaped platesas shown in FIG. 4, with shafts 41 and 42 and the aforementioned shaft35 connected across the plates. The shaft 35 also serves as a pivot; thefloat 3 moves up and down around the shaft 35. The shafts 41 and 42 alsoserve as upper and lower limit stops, respectively, for the float 3. Onthe side, the bracket 38 consists of two L-shaped plates, across whichthe shaft 43 and the first shaft 37 are mounted for connecting these twoplates. The shaft 43 also functions as a stopper for a first arm 52,described below.

The snap mechanism 5 includes a main arm 51, a first arm 52, a coilcompression spring 54, a spring bracket member 55, and a spring bracketmember 56. The main arm 51 consists of two plates parallel with eachother as shown in FIG. 4. On the left-hand end (in FIG. 1) of the twoplates a slot 57 is provided. The main arm 51 is pivotally supported bythe first shaft 37 at the angled section of main arm 51, thereby forminga first pivot connection. In the slot 57 of the main arm 51 is fittedthe shaft 40 of the float arm 34. Because of this connection, the mainarm 51 follows up and down motions of the float 3, rocking up and downon the first shaft 37.

The left end (in FIG. 1) of the main arm 51 swings downward as the float3 rises. On an opposite end of main arm 51 is mounted a second shaft 58parallel with the first shaft 37. The spring bracket member 55 ispivotally supported by the second shaft 58, thereby forming a secondpivot connection. The first arm 52 is pivotally supported on the firstshaft 37. The first arm 52 consists of two parallel plates facing eachother as shown in FIG. 4, each of which is of an inverted L shape. Thelower end of the first arm 52 has mounted on it the third shaft 59,parallel with the first and second shafts 37 and 58, and the springbracket member 56 is pivotally supported on the third shaft 59, therebyforming a third pivot connection. Between the spring bracket members 55and 56 is mounted the coil compression spring 54. The distance betweenthe first shaft 37 and the third shaft 59 is longer than the distancebetween the first shaft 37 and the second shaft 58. On the upper end ofthe first arm 52 a shaft 60 is mounted, to which the lower end of thevalve spindle operating rod 28 is connected. The main arm 51 has awindow 81, which is open so as not to interfere with the operation ofthe shaft 60.

On the liquid holding space 10 side of the liquid discharge port 17 isprovided a valve 6 which is a double valve. The valve 6 is composed ofupper and lower valve cases 61 and 62, upper and lower valve heads 63and 64, and a drain valve shaft 71. The upper valve case 61 and thelower valve case 62 are fastened together by screws or bolts (not shown)the upper valve case 61 is secured to the cover section 8 by screws orbolts (not shown). In the upper valve case 61 is formed an upper valveseat 66, while in the lower valve case 62 is formed a lower valve seat67. The valve seats 66, 67 are in direct communication with the liquidholding space 10 such that liquid from the liquid holding space 10 flowsout the fluid discharge port directly from the liquid holding space 10directly through the openings surrounded by valve seats 66, 67. Theupper valve head 63 is connected by screw threads to a link 65, whichlink 65 is locked from rotating by a nut 68. On the lower shaft portionof the upper valve head 63 the lower valve head 64 is threadedlyconnected. A connecting tube 69 is provided between the upper valve head63 and the lower valve head 64 to space the upper valve head 63 and thelower valve head 64 from one another at a specific distance, to therebyensure accurate seating of both valve heads 63, 64 on the correspondingvalve seats 66, 67 without the need for close tolerancing of the valveheads 63, 64.

As shown in FIGS. 14A-C and 15, the connecting tube 69 has an outercircumferential lower end 69 a formed with a narrowed cone shape definedby an angle θ₁. This lower end 69 a mates with a recess 64 a in theupper end of the lower valve head 64, which recess 64 a is formed as aconical hole defined by an angle θ₂. As the lower valve head 64 isthreaded onto the lower shaft portion of the upper valve head 63, theconical surface of the recess 64 a in the lower valve head 64 is forcedagainst the lower end 69 a of the connecting tube 69 so as to deform thelower end 69 a inwardly. This arrangement between the connecting tube 69and lower valve head 64 creates a seal between the members, therebypreventing leakage through the valve 6.

The upper end of the link 65 is pivotally connected to the drain valveshaft 71, and furthermore the upper end of the drain valve shaft 71 ispivotally connected by a shaft 72 to the float arm 34. The shaft 72 islocated slightly oblique and downward of the shaft 35 when the float 3is in the lowermost position as shown in FIG. 2, and is almostimmediately below the shaft 35 when the float 3 comes to the topmostposition as shown in FIG. 3. The upper and lower valve heads 63 and 64move downwards with the rise of the float 3, communicating the liquidholding space 10 with the liquid discharge port 17, and move upwardswith downward movement of the float 3, thus closing the liquid dischargeport 17.

Next, operation of the present embodiment of the pump 1 will beexplained according to a series of operational procedures in which steamis used as a working fluid. First, the external piping of the pump 1 isconnected, on the working fluid inlet port 11 side, to high-pressuresteam source, and, on the working fluid discharge port 13 side, to thesteam circulation piping. The liquid inlet port 16 is connected to aload, such as a steam-using apparatus, via a check valve (not shown)which opens towards the liquid holding space 10. The liquid dischargeport 17 is connected to equipment to which liquid is pumped—such as aboiler—via a check valve (not shown) which opens away from the liquidholding space 10.

When no condensate is present in the liquid holding space 10 of thecombination pump and trap of the present invention, the float 3 is inthe bottom position as shown in FIG. 1. At this time, the working fluidfeed valve 20 in the change-over valve 4 is closed, while the exhaustvalve is open. The valve 6 is in a closed position, thereby preventingliquid from exiting through liquid discharge port 17. When condensate isproduced in the load, such as a steam-using apparatus, the condensateflows down through the liquid inlet port 16 to the pump 1, accumulatingin the liquid holding space 10.

As the float 3 rises with the accumulation of the condensate in theliquid holding space 10, the float arm 34 rotates clockwise on thecenter of the shaft 35, the shaft 72 connected to the drain valve shaft71 moves downwards, and the upper and lower valve heads 63 and 64 movedownwards, through movement of the drain valve shaft 71 and the link 65,thus opening the valve 6. This allows communication between the liquidholding space 10 and the liquid discharge port 17. The float 3 positionand buoyancy is selected so that the valve 6 does not open until theliquid level in the liquid holding space 10 is above the level of theupper valve head 63, thereby ensuring a liquid seal at valve 6.Furthermore, the configuration of the float arm 34 and the drain valveshaft 71 are such that the initial rise of float 3 will cause rapidopening of the valve 6, and, vice versa, the valve 6 will rapid closeonly as the float approaches its bottommost position.

On the snap mechanism 5, the main arm 51 rotates counterclockwise on thecenter of the first shaft 37 through interlock with the downwardmovement of the shaft 40, driven by rotation of the float arm 34, andthe second shaft 58 moves to the right to align with the first shaft 37and the third shaft 59, compressing the coil spring 54. Then, withfurther rise of the float 3, the second shaft 58 moves to the right pastthe position of alignment with the first shaft 37 and the third shaft59, the coil spring 54 extends suddenly to recover from a compressedstate, thus allowing the clockwise rotation of the first arm 52 aroundshaft 37 to snap the third shaft 59 to the left. As a result, valvespindle operating rod 28 connected to the shaft 60 of the first arm 52moves upwards, to thereby open the working fluid feed valve 20 and toclose the working fluid exhaust valve 21.

With the opening of the working fluid inlet port 11, high-pressure steamis led into the vessel 2. Vessel pressure increases on the condensate inthe liquid holding space 10, thereby forcing the condensate, with steampressure, out the liquid discharge port 17 to an exterior boiler orwaste heat recovery system via a check valve (not shown).

With discharge of the condensate, the water level in the condensateholding space 10 goes down, to lower the float 3. The float arm 34rotates in the counterclockwise direction on the center of the shaft 35,thereby moving upwards the shaft 72 which is connected to the drainvalve shaft 71. Upward movement of drain valve shaft 71 moves the upperand lower valve heads 63 and 64 upwards via the link 65, thus closingthe valve 6. In the process of operation of the valve 6 from thefull-open position to the full-close position, the shaft 72 moves from aposition nearly directly below the shaft 35 as shown in FIG. 3 to aposition obliquely a little below the shaft 35 as shown in FIG. 2, andtherefore the more the valve 6 approaches the full-close position, themore it displaces towards closing the valve. In other words, when thefloat 3 goes downwards from the level shown in FIG. 2, the valve 6 isheld close to the full-open position during the initial period ofdownward movement, thus allowing quick discharge of the condensate.

On the snap mechanism 5 side, the main arm 51 rotates clockwise on thefirst shaft 37, in interlock with the upward movement of the shaft 40,driven by the rotation of the float arm 34. The second shaft 58 moves tothe left into alignment with the first shaft 37 and the third shaft 59,compressing the coil spring 54. With further downward movement of thefloat 3, the second shaft 58 moves to the left past the position ofalignment with the first shaft 37 and the third shaft 59, and then thecoil spring 54 suddenly extends to recover from compression, driving thefirst arm 52 to turn in the counterclockwise direction to snap the valvespindle operating rod 28, connected to the shaft 60 of the first arm 52,downwards. Thus the working fluid feed valve 20 is closed, while theworking fluid exhaust valve 21 is opened.

In the above-described embodiment, the coil spring 54 is disposedbetween the second shaft 58 on the main arm 51 and the third shaft 59 onthe first arm 52. Next, a configuration in which the coil spring 54 isdisposed between the first shaft 37 on the main arm 51 and the secondshaft 58 on the main arm 51, which is apart from the first shaft 37,will be explained with reference to FIG. 5. In the embodiment to bedescribed below, members operating similarly to those explained in theabove-described embodiment are designated by similar numerals in orderto prevent redundancy. FIG. 5 is a sectional view of another embodimentof the pump of the present invention.

The snap mechanism 5 includes the main arm 51, the first arm 52, asecond arm 73, the coil compression spring 54, the spring bracket member55, and the spring bracket member 56. The main arm 51 is composed of twoparallel plates, each of which is L-shaped when viewed from the front.The angled section of the main arm 51 is pivotally supported by thefirst shaft 37. On the lower end of the main arm 51, the second shaft 58is mounted, parallel with the first shaft 37. The second shaft 58 ismovable only in the direction of the first shaft 37 along a long hole orslot 74 formed in the main arm 51. The coil compression spring 54 ismounted between the spring bracket member 55, supported on the firstshaft 37, and the spring bracket member 56, supported on the secondshaft 58.

The first arm 52 is pivotally supported on the first shaft 37 at theangled section of first arm 52. On the lower end of the first arm 52 thethird shaft 59 mounted in parallel with the first and second shafts 37and 58. Between the third shaft 59 and the second shaft 58 the secondarm 73 is mounted. The second arm 73 is composed of two parallel plateswhich are rotatable on the second and third shafts 58 and 59. Thedistance between the first shaft 37 and the third shaft 59 longer thanthe distance between the first shaft 37 and the second shaft 58.

In the present invention, it should be noted that the second shaft 58,operating with rotation of the main arm 51, is aligned with the firstshaft 37 and the third shaft 59 while moving towards the first shaft 37along the long hole 74, to thereby compress the coil spring 54. The coilspring 54, therefore, is axially compressed to deform in the directionof the first shaft, only in the direction of extension and contraction.The coil spring 54 does not curve, and constantly maintains astraight-line state to thereby prevent damage of the coil spring as aresult of bending of the coil spring 54.

Next, an explanation will be given by referring to FIG. 6 of a coilspring 54 disposed between the third shaft 59 on the first arm 52 and afourth shaft 75 on the first arm 52, apart from the third shaft 59. FIG.6 is a sectional view of another embodiment of the pump of the presentinvention.

The snap mechanism 5 includes the main arm 51, the first arm 52, thesecond arm 73, the coil compression spring 54, the spring bracket member55, and the spring bracket member 56. The angled section of the main arm51 is pivotally supported by the shaft 37. At the lower end of the mainarm 51 is installed the second shaft 58 parallel with the first shaft37.

The first arm 52 is pivotally supported to the first shaft 37 at theangled section of the first arm 52. At the intermediate part of thefirst arm 52 is installed the third shaft 59 parallel with the first andsecond shafts 37 and 58. At the lower end of the first arm 52 isinstalled the fourth shaft 75 parallel with the first, second and tothird shafts 37, 58 and 59. The third shaft 59 is movable only in thedirection of the fourth shaft 75 along the long hole 76 formed in thefirst arm 52. Between the third shaft 59 and the second shaft 58, thesecond arm 73 is pivotally installed. Between the spring bracket member55 supported on the fourth shaft 75 and the spring bracket member 56supported on the third shaft 59 is mounted the coil compression spring54. The distance between the first shaft 37 and the third shaft 59 islonger than that between the first shaft 37 and the second shaft 58.

In the present embodiment, it should be noted that the third shaft 59moves in the direction of the fourth shaft 75 along the long hole 76 todeform by compression the coil spring 54 when the second shaft 58,operating in interlock with the rotation of the main arm 51, comes inline with the first shaft 37 and the third shaft 59. The coil spring 54,therefore, is deformed only in the direction of the fourth shaft 75,that is, in the direction of extension and contraction similar to theembodiment shown in FIG. 5. This movement ensures that the coil spring54 is not subject to damage or breakage as the result of bending.

Next, a embodiment with the coil spring 54 disposed between the thirdshaft 59, functionally connected on the first arm 52 by a crank arm 77,and a fourth shaft 75 on the first arm 52, apart from the third shaft59, will be explained by referring to FIG. 7. FIG. 7 is a sectional viewof a further pump of the present invention.

The snap mechanism 5 is composed of the main arm 51, the first arm 52,the second arm 73, the crank arm 77, the coil compression spring 54, thespring bracket member 55 and the spring bracket member 56. The angledsection of the main arm 51 is pivotally supported by the first shaft 37.On the lower end of the main arm 51 is installed the second shaft 58parallel with the first shaft 37. The upper end of the second arm 73 ispivotally supported on the second shaft 58. The third shaft 59 isinstalled on the lower end of the second arm 73, which third shaft 59 isparallel with the first and second shafts 37 and 58.

The first arm 52 is pivotally supported on the first shaft 37 at theangled section of the first arm 52. On the lower end of the first arm 52the fourth shaft 75 is installed parallel with the first second andthird shafts 37, 58 and 59. The coil compression spring 54 is mountedbetween the spring bracket member 55, pivotally supported on the fourthshaft 75, and the spring bracket member 56, pivotally supported on thethird shaft 59. On the portion projecting to the right from theintermediate section of the first arm 52, a fifth shaft 78 parallel withthe first through to fourth shafts 37, 53, 59 and 75 is installed.Between the fifth shaft 78 and the third shaft 59 is mounted the crankarm 77. The crank arm 77 consists of two parallel plates facing eachother, and are rotatable at the points where the third and fifth shafts59 and 78 are connected. The distance between the first shaft 37 and thethird shaft 59 is longer than that between the first shaft 37 and thesecond shaft 58.

In the present embodiment, it should be noted that the third shaft 59moves in the direction of the fourth shaft 75 while rotating about thefifth shaft 78. When the second shaft 58 comes in line with the firstshaft 37 and the third shaft 59, by rotation of the main arm 51, thecoil spring 54 is compressed. The coil spring 54, supported by the crankarm 77 when snapping over, is not subject to lateral bending orvibration and accordingly is prevented from being damaged.

In the above-described embodiment, the float 3 is connected to the mainarm 51 through the float arm 34. Next, a construction in which the float3 is directly connected to the main arm 51 will be explained byreferring to FIGS. 8 and 9. FIG. 8 is a sectional view of another snapmechanism section to be employed in the present embodiment, and FIG. 9is a sectional view taken along line B—B.

In the snap mechanism 5 of FIG. 8 the main arm 51 is supported on thebracket 38 through the first shaft 37. The bracket 38 is integrallymounted on the vessel. The bracket 38 consists of two L-shaped plates asshown in FIG. 9 when viewed from above, the two plates being connectedby the shaft 43 and the first shaft 37. The shaft 43 serves also as astopper for the first arm 52.

The snap mechanism 5 is composed of the main arm 51, the first arm 52,the coil compression spring 54, the spring bracket member 55, and thespring bracket member 56. The main arm 51 is formed by bending a plateinto a U shape as shown in FIG. 9, that is, into two parallel platesfacing each other. In the bent portion of the main arm 51 the float 3 isfastened by a bolt 82. The float 3 rocks up and down on the center ofthe first shaft 37.

The right end (in FIG. 8) of the main arm 51 swings down to the right;on the right end is installed the second shaft 58 which is parallel withthe first shaft 37. The spring bracket member 55 is pivotally supportedon the second shaft 58. Also, the first arm 52 is pivotally supported onthe first shaft 37 at the angled section of the first arm 52. The firstarm 52 consists of two parallel plates as shown in FIG. 9, each of whichis of an inverted L shape. On the lower end of the first arm 52 isinstalled the third shaft 59 which is parallel with the first and secondshafts 37 and 58, and the spring bracket member 56 is pivotallysupported on the third shaft 59. Between the spring bracket members 55and 56 is mounted the coil compression spring 54. Furthermore, on theupper medium part of the first arm 52 is installed the shaft 60, towhich the lower end of the valve spindle operating rod 28 is connected.

The operation of the snap mechanism 5 of the present embodiment differsfrom the above-described embodiment only in the direction of rotation ofthe main arm 51 and the first arm 52 which are operated by the upwardand downward movement of the float 3, and therefore a detailed operationprocedure will not be described.

In the embodiment shown in FIGS. 8 and 9, the float 3 is fastened by abolt 82 to the main arm 51. Next, a way in which the float 3 and themain arm 51 are loosely connected will be explained with reference toFIGS. 10 and 11. FIG. 10 is a sectional view of another snap mechanismsection to be adopted in the pump according to the present invention;FIG. 11 is an exploded perspective view of a member connected to themain arm of FIG. 10.

The snap mechanism 5 includes the main arm 51, the first arm 52, thecoil compression spring 54, the spring bracket member 55, and the springbracket member 56. The main arm 51 is composed of two parallel platesfacing each other. On the left end (in FIG. 10) of the two plates ininstalled a shaft 83, to which a connecting member 84, fixedly attachedto the float 3 by welding, is pivotally installed. The connecting member84 is a round rod having at the forward end a rectangular projection 85formed by cutting off both sides of the rod end. The projection 85 isinserted and pivotally connected by the shaft 83 between the two platesof the main arm 51. The forward end face 86 of the shoulder of theconnecting member 84 contacts the upper and lower faces 87 and 88 on themating end side of the main arm 51, serving as a stopper to preventfurther rotation over a specific position. Thus, the float 3 rocks upand down on the center of the shaft 83 which is supported by the mainarm 51, according to a change in the liquid level in the vessel. Themain arm 51 also rocks up and down on the center of the first shaft 37with the up-and-down motion of the float 3 after the float 3 has moved aspecific amount so that the forward end face 86 of the shoulder sectionof the connecting member 84 contacts the upper face 87 or the lower face88 of the main arm 51.

In the embodiment described above, after movement by a specific amountof the float 3 so that the face 86 contacts one of the faces 87, 88, themain arm 51 rotates upon further rise or fall of the float 3. Therefore,the change-over valve can be operated in the two specific upper andlower positions without extending the connecting section between themain arm 51 and the float 3.

Another construction in which the float 3 and the main arm 51 areloosely connected will be explained with reference to FIG. 12. FIG. 12is a sectional view of another snap mechanism section to be adopted inthe pump according to the present invention.

The main arm 51 includes two parallel plates facing each other insertedat the left end part (in FIG. 12) in a short pipe 88 securely attachedto the float 3 by welding. The main arm 51 and the short pipe 88 arepivotally connected by a shaft 87, and accordingly the float 3 rocks upand down on the center of the shaft 87, supported on the main arm 51,according to a change in the liquid level in the vessel. The main arm 51rocks up and down on the center of the first shaft 37 after the float 3has moved a specific amount until the forward end of the short pipe 88contacts the main arm 51.

The embodiments of FIGS. 10-12 are advantageous in that they allow agreater range of movement for the float 3 within the vessel, therebyallowing more complete filling, and more complete draining, of thevessel than a similarly constructed apparatus with a float rigidlyaffixed to the float arm. This is because the arrangements of theembodiments of FIGS. 10-12 include an additional range of motion of thefloat 3 corresponding to the pivot angle of the float 3 about the pin 83or 87, in addition to the range of motion of the float arm 51 about itsown pivot 37. This additional pivot angle would be included at both theupper and lower ends of the range of motion of the float arm 51.

It should also be noticed in the present embodiment that, similarly tothe embodiment shown in FIGS. 10 and 11, the change-over valve can beoperated in the two specific upper and lower positions without extendingthe connection section between the main arm 51 and the float 3.

It is to be understood that the above-described embodiments representpreferred constructions of the present invention. Other constructionsare possible without falling outside of the scope of the presentinvention, which is defined according to the claims set forth below.

What is claimed is:
 1. A pump comprising: a vessel, said vesselcomprising a motive fluid inlet port, a motive fluid outlet port, aliquid inlet port and a liquid discharge port; a motive fluid inletvalve for opening and closing said motive fluid inlet port and a motivefluid outlet valve for opening and closing said motive fluid outletport, said motive fluid inlet valve opening said motive fluid inlet portwhen said motive fluid outlet valve closes said motive fluid outlet portand said motive fluid inlet valve closing said motive fluid inlet portwhen said motive fluid outlet valve opens said motive fluid outlet port;a motive fluid valve actuation link connected to said motive fluid inletvalve and said motive fluid outlet valve; a float; a main arm, said mainarm being coupled to said float, said main arm being pivotally mountedin said vessel about a first pivot axis by a first pivot connection; afirst arm, said first arm being pivotally mounted in said vessel, saidmotive fluid valve actuation link being connected to said first arm; aresilient element, said resilient element being connected to said mainarm, said resilient element also being connected to said first arm; asecond arm pivotally connected to said resilient element; and a floatarm, said float being mounted on said float arm, said float arm beingpivotally mounted in said vessel, said float arm being coupled to saidmain arm.
 2. The pump of claim 1, wherein: said resilient element is acompression spring.
 3. The pump of claim 1, wherein: said second arm ispivotally mounted on said first arm by a third pivot connection.
 4. Thepump of claim 1, wherein: said second arm is pivotally mounted on saidmain arm by a second pivot connection.
 5. The pump of claim 1, furthercomprising: a shaft connected to the resilient element and disposedwithin a slot provided on one of the main arm and the first arm, theslot preventing a curvature of the resilient element by limiting amotion of the resilient element to a direction coextensive with an axisof the resilient element.
 6. A pump comprising: a vessel, said vesselcomprising a motive fluid inlet port, a motive fluid outlet port, aliquid inlet port and a liquid discharge port; a motive fluid inletvalve for opening and closing said motive fluid inlet port and a motivefluid outlet valve for opening and closing said motive fluid outletport, said motive fluid inlet valve opening said motive fluid inlet portwhen said motive fluid outlet valve closes said motive fluid outlet portand said motive fluid inlet valve closing said motive fluid inlet portwhen said motive fluid outlet valve opens said motive fluid outlet port;a motive fluid valve actuation link connected to said motive fluid inletvalve and said motive fluid outlet valve; a float; a main arm, said mainarm being coupled to said float, said main arm being pivotally mountedin said vessel about a first pivot axis by a first pivot connection; afirst arm, said first arm being pivotally mounted in said vessel, saidmotive fluid valve actuation link being connected to said first arm; aresilient element, said resilient element being connected to said mainarm, said resilient element also being connected to said first arm; asecond arm pivotally connected to said resilient element, said secondarm being pivotally mounted on said main arm by a second pivotconnection; and a crank arm pivotally connected to said resilientelement and pivotally mounted on said first arm.
 7. A pump comprising: avessel, said vessel comprising a motive fluid inlet port, a motive fluidoutlet port, a liquid inlet port and a liquid discharge port; a motivefluid inlet valve for opening and closing said motive fluid inlet portand a motive fluid outlet valve for opening and closing said motivefluid outlet port, said motive fluid inlet valve opening said motivefluid inlet port when said motive fluid outlet valve closes said motivefluid outlet port and said motive fluid inlet valve closing said motivefluid inlet port when said motive fluid outlet valve opens said motivefluid outlet port; a motive fluid valve actuation link connected to saidmotive fluid inlet valve and said motive fluid outlet valve; a float; amain arm, said main arm being coupled to said float, said main arm beingpivotally mounted in said vessel about a first pivot axis by a firstpivot connection; a first arm, said first arm being pivotally mounted insaid vessel, said motive fluid valve actuation link being connected tosaid first arm; a resilient element, said resilient element beingconnected to said main arm, said resilient element also being connectedto said first arm; and a shaft connected to said resilient element, saidshaft sliding in a slot to thereby prevent bending of said resilientelement, wherein: said main arm comprises said slot.
 8. A pumpcomprising: a vessel, said vessel comprising a motive fluid inlet port,a motive fluid outlet port, a liquid inlet port and a liquid dischargeport; a motive fluid inlet valve for opening and closing said motivefluid inlet port and a motive fluid outlet valve for opening and closingsaid motive fluid outlet port, said motive fluid inlet valve openingsaid motive fluid inlet port when said motive fluid outlet valve closessaid motive fluid outlet port and said motive fluid inlet valve closingsaid motive fluid inlet port when said motive fluid outlet valve openssaid motive fluid outlet port; a motive fluid valve actuation linkconnected to said motive fluid inlet valve and said motive fluid outletvalve; a float; a main arm, said main arm being coupled to said float,said main arm being pivotally mounted in said vessel about a first pivotaxis by a first pivot connection; a first arm, said first arm beingpivotally mounted in said vessel, said motive fluid valve actuation linkbeing connected to said first arm; a resilient element, said resilientelement being connected to said main arm, said resilient element alsobeing connected to said first arm; and a shaft connected to saidresilient element, said shaft sliding in a slot to thereby preventbending of said resilient element, wherein: said first arm comprisessaid slot.
 9. An over-center snap link comprising: a main arm, said mainarm being pivoted about a first pivot axis, said main arm beingstructured to join with a float arm that is pivotally mounted within avessel; a first arm, said first arm being pivoted; a resilient element,said resilient element being connected to said main arm, said resilientelement also being connected to said first arm; and a second armpivotally connected to said resilient element.
 10. The over-center snaplink of claim 9, wherein: said resilient element is a compressionspring.
 11. The over-center snap link of claim 9, wherein: said secondarm is pivotally mounted on said first arm by a third pivot connection.12. The over-center snap link of claim 9, wherein: said second arm ispivotally mounted on said main arm by a second pivot connection.
 13. Theover-center snap link of claim 9, further comprising: a shaft connectedto the resilient element and disposed within a slot provided on one ofthe main arm and the first arm, the slot preventing a curvature of theresilient element by limiting a motion of the resilient element to adirection coextensive with an axis of the resilient element.
 14. Anover-center snap link comprising: a main arm, said main arm beingpivoted about a first pivot axis; a first arm, said first arm beingpivoted; a resilient element, said resilient element being connected tosaid main arm, said resilient element also being connected to said firstarm; a second arm pivotally connected to said resilient element, saidsecond arm being pivotally mounted on said main arm by a second pivotconnection; and a crank arm pivotally connected to said resilientelement and pivotally mounted on said first arm.
 15. An over-center snaplink comprising: a main arm, said main arm being pivoted about a firstpivot axis; a first arm, said first arm being pivoted; a resilientelement, said resilient element being connected to said main arm, saidresilient element also being connected to said first arm; and a shaftconnected to said resilient element, said shaft sliding in a slot tothereby prevent bending of said resilient element, wherein: said firstarm comprises said slot.
 16. A pump comprising: a vessel, said vesselcomprising a motive fluid inlet port, a motive fluid outlet port, aliquid inlet port and a liquid discharge port; a motive fluid inletvalve for opening and closing said motive fluid inlet port and a motivefluid outlet valve for opening and closing said motive fluid outletport, said motive fluid inlet valve opening said motive fluid inlet portwhen said motive fluid outlet valve closes said motive fluid outlet portand said motive fluid inlet valve closing said motive fluid inlet portwhen said motive fluid outlet valve opens said motive fluid outlet port;a motive fluid valve actuation link connected to said motive fluid inletvalve and said motive fluid outlet valve; a float; a main arm, said mainarm being coupled to said float, said main arm being pivotally mountedin said vessel about a first pivot axis by a first pivot connection; afirst arm, said first arm being pivotally mounted in said vessel, saidmotive fluid valve actuation link being connected to said first arm; aresilient element, said resilient element being connected to said mainarm, said resilient element also being connected to said first arm; ashaft connected to said resilient element, said shaft sliding in a slotto thereby prevent bending of said resilient element; a second armpivotally connected to said resilient element; and a float arm, saidfloat being mounted on said float arm, said float arm being pivotallymounted in said vessel, said float arm being coupled to said main arm.17. The pump of claim 16, wherein: the slot prevents the bending of theresilient element by limiting a motion of the resilient element to adirection coextensive with an axis of the resilient element.
 18. Anover-center snap link comprising: a main arm, said main arm beingpivoted about a first pivot axis, said main arm being structured to joinwith a float arm that is pivotally mounted within a vessel; a first arm,said first arm being pivoted; a resilient element, said resilientelement being connected to said main arm, said resilient element alsobeing connected to said first arm; a shaft connected to said resilientelement, said shaft sliding in a slot to thereby prevent bending of saidresilient element; and a second arm pivotally connected to saidresilient element.
 19. The over-center snap link of claim 18, wherein:said main arm comprises said slot.
 20. The over-center snap link ofclaim 18, wherein: the slot prevents the bending of the resilientelement by limiting a motion of the resilient element to a directioncoextensive with an axis of the resilient element.